In recent years, along with the high integration and the enhancement of performance of the semiconductor integrated circuit (LSI), a novel microfabrication technology has been developed. A chemical mechanical polishing (CMP) method is one of them and becomes a technology frequently utilized in an LSI production step, particularly planarization of an interlayer insulating film layer, metal plug formation, and trench formation in a multilayer wiring forming step (for example, see Patent Literature 1).
A polishing liquid for a metal used for CMP has generally an oxidant and a solid abrasive particle and if necessary, thereto, further a metal oxide dissolving agent and a protective film forming agent (metal anticorrosive) are added. A fundamental mechanism of polishing is considered to comprise first, oxidizing a metal layer surface by an oxidant and then removing the resultant oxidized layer by a solid abrasive particle.
An oxidized layer in the metal layer surface deposited on a groove (concavity) is not so much contacted with a polishing pad, so that the effect of scraping by a solid abrasive particle does not extend thereto. However, in an oxidized layer in the metal layer surface deposited on a convexity and contacted with a polishing pad, scraping is progressed. Accordingly, along with a progress in CMP, a metal layer on the convexity is removed and the surface of the substrate is planarized (for example, see Non Patent Literature 1).
On the other hand, along with the high integration of a semiconductor device, an increase in the number of pins, narrowing of the pitch, and thin implementation are required. Further, the prevention of a wiring delay between a semiconductor device and a wiring substrate and a noise has become also an important task. Therefore, as the bonding between the semiconductor device and the wiring substrate, instead of a conventional mounting predominantly of wire bonding, a flip-chip mounting has been widely adopted.
Then, in this flip-chip mounting, there is widely used a solder bump bonding method in which a convex electrode is formed on an electrode terminal of a semiconductor device and through this convex electrode, all bondings are collectively performed to a bonding terminal formed on the wiring substrate.
As the CMP polishing liquid aiming at a layer composed of titanium nitride or tantalum nitride, etc. and formed on a substrate as a polishing object, there is known a polishing liquid in which a protective film forming agent and an organic acid are added (see Patent Literature 2).
In addition, as an attempt to apply CMP to a layer composed of copper, there is known a method using, for example, a polishing liquid in which 2-quinolinecarboxylic acid is added (see Patent Literature 3). In addition, as an attempt to apply CMP to a nickel layer, there is known a method using, for example, a polishing liquid in which abrasive particles, an organic acid, and an oxidant are added as a polishing liquid for an HDD magnetic head (see Patent Literature 4).
Here, palladium is generally classified together with platinum, ruthenium, etc. into “noble metal”. As an attempt to apply CMP to such a noble metal layer, there is known a method using, for example, a polishing liquid in which a sulfur compound is added, a polishing liquid in which any one of a diketone, a nitrogen-containing heterocyclic compound, or an amphoteric ion compound is added, or a polishing liquid in which an oxide of a metal belonging to the Platinum Group is added (see Patent Literatures 5, 6, and 7).